Process for the preparation of anionic aqueous polymer dispersions containing no volatile tertiary amine, obtained dispersion and coating resulting from said dispersion

ABSTRACT

The invention relates to a process for the preparation of an aqueous dispersion of an anionic polyurethane in which initially a tertiary aminofunctional acrylic monomer is used as neutralizing agent for pendant carboxylic acid groups in dispersions of a polyurethane or a polyurethane/polyacrylate, whereafter the unsaturated monomers undergo in situ an addition polymerisation, optionally together with other unsaturated monomer. In the process the isocyanate terminated prepolymer may be reacted with 0-100% of a stoichiometric amount of a hydroxy functional unsaturated monomer before the dispersion in water. The tertiary amine functional usaturated monomer is preset in a ratio to the anionic residues to be neutralized in the polyurethane prepolymer from 0.3 to 2 and preferably from 0.7 to 1.5. Furthermore the amount of carboxylic acid functions in the isocyanate functional polyurethane prepolymer is from 1 to 15% and preferably from 2 to 10%. The invention also relates to dispersions prepared by the present process and to a coating or film obtained from said dispersion.

The present invention relates to a process to prepare aqueousdispersions of anionic polyurethanes and polyurethane-polyacrylatehybrids containing tertiary amino functional acrylic oligomers, polymersor copolymers as acid-neutralizing agents, in the absence of volatiletertiary amines.

INTRODUCTION

Aqueous dispersions of polyurethanes or polyurethane-polyacrylatehybrids are well known as basis for the production of coatingcompositions. They may be used for protective or decorative coating,optionally in combination with additives like coloring agents, pigments,matting agents, and the like. Polyurethanes can possess many desirableproperties such as good chemical resistance, water resistance, solventresistance, toughness, abrasion resistance, durality. Thermoplasticpolyurethane-polyacrylate hybrid dispersions became of interestregarding to polyurethanes because of their lower raw material costs andthey became of interest regarding to polyacrylates because of theirbetter performance.

As is by now well known in the art, aqueous polyurethane dispersions areparticularly advantageously prepared by dispersing anisocyanate-terminated polyurethane prepolymer bearing ionic and/ornon-ionic dispersing groups into an aqueous medium and than reacting theprepolymer with an active hydrogen containing chain extender whiledispersed in the aqueous medium. See e.g. UK-patents 1549458 and1549459.

Generally polyurethane-polyacrylate hybrids are prepared by an additionpolymerisation of acrylic monomers in a polyurethane dispersion. Theacrylic monomers can be added to the polyurethane dispersion, which isdescribed in for example DE 1953348, EP643734 but they can also be addedduring the preparation of the polyurethane dispersion at several stages,which is described in for example U.S. Pat. No. 4,644,030, EP742239. Thevinylic monomers can be added during or after the polyurethaneprepolymer formation and in these cases they function as viscosityreducing solvents. The advantage is that no or less other organicsolvents have to be used, and a better homogeneity is obtained. Theaddition polymerisation is executed after the formation of the aqueouspolyurethane. Moreover, further vinylic monomers may be added during thepolymerisation as described in for example EP 308115.

Dispersibility of the polyurethanes or polyurethane-polyacrylate hybridsin water can be achieved by incorporation of appropriate chain pendantionic groups, chain pendant non-ionic hydrophilic groups, or in-chainnon-ionic hydrophilic groups in the structure of the polyurethanepolymer. If suitable, external surfactants can be applied in addition.Preferably anionic groups are incorporated into the polyurethanebackbone, such as carboxylic, sulfonic, sulfate or phosphate groups, byreaction of an isocyanate reactive compound having at least one acidgroup with a polyisocyanate. Most common is the incorporation of acarboxylic acid functional compound.

The carboxylic acid functions are generally neutralized before or duringdispersion of the polyurethane prepolymer or prepolymer-vinylic monomersolution in water with a volatile tertiary amine. Anorganic bases areless convenient, since the polyurethane will coagulate when they areapplied or it will provide highly water sensitive films or coatings. Toprevent coagulation it is suitable to incorporate a great number ofhydrophilic polyethoxy chains into the polymer system.

A disadvantage of the application of volatile tertiary amines asneutralizing agent is that they evaporate during the film formation, andtherefore will cause environmental pollution,

The present invention offers a process to prepare aqueous dispersions ofanionic polyurethanes or of polyurethane-polyacrylate hybrids containingno volatile tertiairy amines.

DESCRIPTION OF THE INVENTION

The object of the present invention is to provide a process to prepare adispersion of a polyurethane or a polyurethane-polyacrylate hybridewhich contains no volatile tertiary amines as neutralizing agents forcarboxylic acid groups.

Accordingly the present invention relates to a process for thepreparation of an aqueous dispersion of an anionic polyurethane in whichinitially a tertiary amino-functional acrylic monomer of formula I

wherein,

R, R¹, R², R³, R⁴ and R⁵ are organic groups which have no reactivitytowards the double bond or the tertiary amine function, is used asneutralizing agent for pendant carboxylic acid groups in dispersions ofa polyurethane or a polyurethane/polyacrylate, whereafter theunsaturated monomers undergo in situ an addition polymerisation,optionally together with other unsaturated monomers,

characterized in that the aqueous dispersion of the anionic polyurethaneis prepared by the steps of

preparation of an isocyanate functional anionic polyurethane prepolymer,optionally in the presence of vinylic monomers

mixing of the isocyanate terminated anionic polyurethane prepolymer witha tertiary-amino functional unsaturated monomer and optionally othervinylic monomers

followed by dispersion of the obtained mixture into water, and chainextension of the polyurethane prepolymer with an active hydrogencompound during or after the dispersion in water,

initiating radical polymerisation of the vinylic monomers, including thetertiary amino functional unsaturated monomers.

Advantage of this process is that after the polymerisation of theunsaturated monomers containing a tertiary amine the dispersions containno volatile amines and therefore environmental problems will beeliminated. Another advantage of the process is that the unsaturatedmonomers containing a tertiairy amine function act as viscosity reducingsolvents during the formation of the aqueous polyurethane. This effectis improved when other unsaturated monomers are present as well and anaqueous dispersion of a polyurethane-polyacrylate hybride is formed. Inboth situations less or sometimes even no other organic solvents have tobe be used, and a better homogeneity is obtained.

A further part of the invention is a process in which the isocyanateterminated prepolymer is reacted with 0-100% of a stoichiometric amountof a hydroxy functional unsaturated monomer before the dispersion inwater.

As a result the polyurethane prepolymer is completely or partiallyfunctionalized with acrylic double bonds by complete or partial reactionof the isocyanate functions of the prepolymer with a hydroxy functionalunsaturated monomer. As a result the polyurethane polymer system willcontain double bonds and will contribute to the addition polymerisation.

The acid groups in the prepolymer are initially neutralized by atertiary amine functional unsaturated monomer. In the process of theinvention a tertiary amine functional acrylic polymer is formed duringthe process by radical polymerisation of the tertiary-amino functionalunsaturated monomers. When other unsaturated monomers are present acopolymer will be formed during the process including the tertiary aminefunctional unsaturated monomers and the other unsaturated monomers. Theother vinylic monomers which may be present are selected from acrylicalkyl esters, methacrylic alkyl esters, styrene esters or ethers ofvinyl alcohol. The other vinylic monomers are present in an amount of 0to 90%.

The present invention further comprises the dispersions prepared by theprocess and coatings or films derived from dispersions prepared by theprocess.

At low levels of other vinylic monomers or, without the presence ofvinylic monomers, the performance of the films or coatings of thedispersions will be comparable with the performance of the films orcoatings of polyurethane dispersions. At higher levels of other vinylicmonomers the performance of the films or coatings of the dispersionswill be comparable with the performance of the films or coatings ofpolyurethane-polyacrylate hybride dispersions.

Both the polyurethane and the acrylic monomers may contain additionalfunctional groups with the objective to improve the waterdispersibility,to improve adhesion to substrates at application, for performancereasons, or as potential sites for crosslinking. Suitable functions arepolyalkoxy functions with a large concentration of ethoxy functions, aretertiairy amine or quaternairy amine functions, perfluor functions,incorporated silicon functions, hydrazide functions or hydrazonefunctions, ketone, acetoacetate, hydroxy, methylol, amide, glycidyl,ureido or aldehyde functions.

DETAILED DESCRIPTION OF THE INVENTION

The tertiary amine functional unsaturated monomer which is used in theprocess of the invention can be a dialkylaminoalkyl acrylate, adialkylaminoalkyl methacrylate, a dialkyl aminoalkoxy acrylate and/or adialkylaminoalkoxy methacrylate. Suitable examples aredimethylaminoethyl acrylate, dimethyl-aminoethyl methacrylate,diethylaminoethyl acrylate, diethyl-aminoethyl methacrylate,2-(diethylamino)ethanol vinylether and the like.

The tertiary amine functional unsaturated monomers are present in aratio to the anionic residues to be neutralized in the polyurethaneprepolymer from 0.3 to 2 and preferably from 0.7 to 1.5

When the isocyanate functional polyurethane prepolymer is reacted with ahydroxy functional unsaturated monomer the reaction is carried out bytechniques well known in the art at 40 to 130° C. The hydroxy functionalunsaturated monomer may be hydroxyethyl methacrylate, hydroxypropylacrylate, hydroxypropyl methacrylate, hydroxybutyl acrylate, hydroxybutyl methacrylate, hydroxypolyester acrylates or methacrylates.

The polyurethane and/or polyurethane-polyacrylate hybride containsanionic groups to obtain water dispersibility. This anionic group can bea carboxyl, a sulfonic, a sulfate and/or a phosphate group and ispreferably a carboxyl group.

The isocyanate functional polyurethane prepolymer containing carboxylicacid groups is prepared in a conventional way. EP 308115 presents anoverview of the process and of suitable polyols and polyisocyanates asstarting materials for such polyurethane prepolymers. Ketone functionalpolyester polyols are included as well. Suitable hydrogen reactive chainextenders and the conditions wherein they are used are described in thesame application.

The amount of carboxylic acid functions in the isocyanate functionalpolyurethane prepolymer is from 1 to 15% and preferably from 2 to 10%.The carboxylic acid functions are introduced in the prepolymer byincorporation of a dihydroxy alkanoic acid, which may be a2,2-dimethylol alkanoic acid and is preferably 2,2-dimethylol propanoicacid.

In order to obtain polyurethane-polyacrylate hybrids, other vinylicmonomers may be added. They can be added completely or partially to thepolyurethane prepolymer or, preferably the polyurethane prepolymer isformed in the presence of the vinylic monomers. By combining thepolyurethane prepolymer with the vinylic monomers an optimal homogenityis obtained and the viscosity will be reduced. As a consequence lessadditional solvents will be needed. The vinylic monomers can be furtheradded completely or partially after dispersion of the polyurethaneprepolymer in water, during or after the chain extension. They furthercan be partially added during the radical polymerisation process.

Suitable vinylic monomers which can be used in addition are selectedfrom acrylic or methacrylic alkyl esters, acrylic or methacrylic alkylesters, optionally functionalized with hydroxy, quaternary amines orhalogen groups, acrylonitrile, styrene, esters and ethers of vinylalcohol.

The final proportion of additional vinylic monomers may vary from 0 upto 90%, and preferably from 0 to 60%.

The tertiary amine functional unsaturated monomer may be mixed with thepolyurethane prepolymer, optionally in the presence of other vinylicmonomers and be dispersed in water using techniques well known in theart. Preferably, water is stirred into the mixture with agitation or,alternatively, the mixture is added to the water and optionally thechain extender with agitation. Alternatively the polyurethaneprepolymer, optionally in the presence of other vinylic monomers isadded to a mixture of water and the tertiary amine functionalunsaturated monomer and optionally the chain extender with agitation.

Regularly the ratio of tertiairy amine functions to the acid groups inthe polyurethane prepolymer is from 0.3 to 2 and preferably from 0.7 to1.5. At lower levels of the tertiary amine functional acrylate, thefinal dispersion will have a lower pH value, which may be advantageousfor some crosslinking applications.

Polymerisation of the tertiary amine functional unsaturated compound orcombination of the tertiary amine functional unsaturated compound andother vinylic monomers may be effected by the methods described inEP308115.

The polyurethane and/or the acrylic monomers of the invention maycontain additional functional groups which may be polyalkoxy functionswith a large concentration of ethoxy functions, may be tertiary amine orquaternary amine functions, perfluor functions, incorporated siliconfunctions, hydrazide functions or hydrazone functions, ketone,aceto-acetate, hydroxy, methylol, amide, glycidyl, ureido or aldehydefunctions.

Conventional non-ionic, anionic or cationic surfactants may be appliedto optimize dispersion of the polymer system in water and stabilisationof the final polymer dispersion. Suitable examples may be based onlong-chain dialkyl sodium sulphosuccinate, arylalkylpoly-ethoxyalkylderivatives, highly ethoxylated polyurethane derivatives and the like.

The aqueous polymer dispersions produced by the method of the inventionare stable for long periods of time. If desired minor amounts ofsolvents may be included in the dispersions.

Many additional ingredients may also be present in the applicationstage, for example fillers, colorants, pigments, silicons, flow agents,foam agents, fire retardants and the like.

The aqueous polymer dispersions produced by the method of the inventionmay be used in adhesives, sealants, printing ink and in coatings. Theymay be applied on any substrates, including leather or artificialleather, metals, wood, glass, plastics, paper, paper board, textile,non-woven, cloth, foam and the like by conventional methods, includingspraying, flow-coating, roller-coating, brushing, dipping, spreading andthe like.

Various aspects of the present invention are illustrated by thefollowing examples. These examples are only illustrative and are notlimiting the invention as claimed hereafter.

EXAMPLES Example 1

Preparation of an aqueous polyurethane dispersion containing acopolymerized tertiary amine functional methacrylate.

26.33 g (118.5 mmole) of3-isocyanatomethyl-3,5,5-trimethylcyclohexylisocyanate (hereafterreferred to as IPDI) was added to a mixture of 53.2 g (26.6 mmole) of apolycarbonate diol with a molecular weight of about 2000 (obtainablefrom Stahl USA as PC-1122) and 5.28 g (37.45 mmole) of2,2-dimethylol-propanoic acid in 12 g of N-methylpyrrolidone at 60° C.while mixing. The mixture was heated to 90° C. and the mixture wasreacted at 90° C. for 2 hrs. After 1 hr of reaction 0.01 g of tinoctoatewas added as a catalyst. The reation mixture was cooled down. The amountof NCO in the obtained prepolymer was 4.32%.

2.43 g (15.46 mmole) of dimethylaminoethyl methacrylate (hereafterreferred to as DMAEMA) was mixed with 39.27 gram of the the prepolymerat 55° C. for 20 min. The neutralized prepolymer was dispersed into57.28 g of demineralized water and the polyurethane prepolymer was chainextended by the addition of 0.96 g (19.2 mmole) of hydrazine hydrate.The mixture was stirred for 30 min. The absence of residual NCO waschecked by IR-spectroscopy.

12 g of butyl acrylate and 22.3 g of water were mixed in thepolyurethane and the tertiary amine functional methacrylic monomer waspolymerized together with the butyl acrylate within one hour at 75-80°C., using 0.03 g of t-butylhydroperoxide and 1.01 g of a 1% solution inwater of isoascorbic acid as redox initiation system. The obtainedproduct had a solids amount of 34% and a pH of 6.9.

Example 2

Preparation of an aqueous polyurethane dispersion containing acopolymerized tertiary amine functional methacrylate.

The process for the preparation of the polyurethane dispersion ofexample 1 was repeated up to and including the extension with hydrazine.2.43 g of butyl acrylate, 2 g of dioctyl sodium sulphosuccinate and 10 gof water were added to the polyurethane dispersion and the tertiaryamine functional methacrylic monomer was polymerized together with thebutyl acrylate within one hour at 75-80° C., using 0.03 g oft-butylhydroperoxide and 1.01 g of a 1% solution in water of isoascorbicacid as redox initiation system. The obtained product was adjusted withwater to a solids amount of 35% and it had a pH of 6.9.

Example 3

Preparation of an aqueous polyurethane dispersion containing acopolymerized tertiary amine functional methacrylate.

The process of example 2 was repeated with the exception that thepolyurethane prepolymer was prepared from 22.89 g (103 mmole) of IPDI,60.00 g (30 mmole) of polycarbonate diol and 3.6 g (25.53 mmole) of2,2-dimethylolpropanoic acid in 10 g of N-methylpyrrolidone and theNCO-amount of the obtained prepolymer was 3.58%. Further, 1.66 g (10.56mmole) of DMAEMA was mixed with 38.4 g of the prepolymer and 59.08 g ofwater was used for the dispersion. The obtained polyurethane dispersionwas mixed with 1.63 g of butyl methacrylate and 2 g of dioctyl sodiumsulphosuccinate, whereafter the tertiary amine functional methacrylicmonomer was polymerized together with the butyl methacrylate within onehour at 75-80° C., using 0.03 g of t-butylhydroperoxide and 1.01 g of a1% solution in water of isoascorbic acid as redox initiation system. Theobtained product was adjusted with water to a solids amount of 35% andit had a pH of 7.

Example 4

Preparation of an aqueous polyurethane dispersion containing acopolymerized tertiary amine functional methacrylate.

The process of example 2 was repeated with the exception that the DMAEMAwas replaced by 2.86 g of diethyl-aminoethyl methacrylate.

Example 5

Preparation of a hydrazon functional chain extender 100 g (1 mole) ofethylacrylate was added within 45 min to 170 g (1 mole) of isophorondiamine at 40-45 C. The mixture was stirred for 4 hrs at 40-45° C. Thereaction was checked by the disappearance of the double bond signals at960 and 1600 cm⁻¹ in the infrared spectrum. The intermediate product wasa ethyl N-aminopropionate functional isophorone diamine. 50 g ofhydrazine hydrate (1 mole) was added to the product at 55° C. and theproduct was heated and stirred at 55-60° C. during 5 hrs. The reactionwas checked by the disappearance of the carbonyl signal at 1740 cm⁻¹from the ester carbonyl and de appearance of the carbonyl signal fromthe hydrazide carbonyl at 1650 cm⁻¹ in the infrared spectrum. The secondintermediate product was a N-hydrazido-propionate functional isophoronediamine. 58 g (1 mole) of aceton was added to the obtained product atambient temperature and the mixture was stirred for 15 min. The productwas a isophorone diamine substituted at one N by an 3-propionylhydrazone. The product contained 2.65 meq/g of hydrazone functions and5.29 meq/g of amine functions.

Example 6

Preparation of an hydrazone functional aqueous polyurethane dispersioncontaining a copolymerized tertiary amine functional methacrylate.

The process of example 5 was repeated with the exception that thehydrazine was replaced by a mixture of 7.26 g of the product of example5 and 7.26 g of water. The obtained product had a solids amount of35.4%, a hydrazone functionality of 0.145 meq/g and a pH of 7.9.

Example 7

Preparation of an aqueous polyurethane dispersion containing acopolymerized tertiary amine functional methacrylate.

33.27 g (149.7 mmole) of IPDI was added to a mixture of 45.4 g (22.7mmole) of a polytetramethylene glycol with a molecular weight of about2000 (obtainable as Terathane 2000 from Du Pont de Nemours) and 6 g(27.0 mmole) of 2,2-dimethylol-propanoic acid in 12 g ofN-methylpyrrolidone at 60° C. while mixing. The mixture was heated to90° and the mixture was reacted at 90° C. for 2 hrs. After 1 hr ofreaction time 0.01 g of tinoctoate was added as a catalyst. The reactionmixture was cooled down. The amount of NCO in the obtained prepolymerwas 7.00%.

1.67 Gram (11.7 mmole) of dimethylaminoethyl acrylate and 8 g ofbutylacrylate were mixed with 26.10 gram of the prepolymer at 55° C. for20 min. The neutralized prepolymer was dispersed into 71.30 g ofdemineralized water and the polyurethane prepolymer was chain extendedby the addition of 1.03 g (20.6 mmole) of hydrazine hydrate. The mixturewas stirred for 30 min. The absence of residual NCO was checked byIR-spectroscopy.

8.34 g of butyl acylate was added to 69.52 g of the polyurethanedispersion and the tertiary amine functional methacrylic monomer and thebutyl acrylate monomer were polymerised within one hour at 75-80° C.,using t-butyl-hydroperoxide and isoascorbic acid as redox initiationsystem. The obtained product had a solids amount of 34.0% and a pH of7.0.

Example 8

Preparation of an aqueous polyurethane dispersion containing acopolymerized tertiary amine functional methacrylate.

The process of example 7 was repeated with the exception that thebutylacrylate which was mixed with the polyurethane prepolymer and thedimethylaminoethyl acrylate was replaced by ethylhexylacrylate.

The product was adjusted to a solids amount of 35% with water and the pHwas 7.2.

Example 9

Preparation of an aqueous polyurethane dispersion containing a copolymerof a tertiary amine functional methacrylate, butylacrylate and aacetoacetyl functional methacrylate. The process of example 2 wasrepeated with the exception that before the initiation of the additionpolymerisation the butylacrylate was replaced by 1 g ofacetoacetoxyethyl methacrylate, 10 g of butylacrylate and 18 g of waterwas added to the dispersion and the DMABMA was polymerised together withthe acetoacetoxyethyl methacrylate and the butyl acrylate The obtainedproduct had a solids amount of 35.2%, a pH of 7.1 and a acetoacetatefunctionality of 0.215 meq/g

Example 10

Preparation of an aqueous dispersion of a polyurethane containingpendant ketone functions and containing a copolymer of a tertiary aminefunctional methacrylate and butylacrylate.

Under a nitrogen atmosphere 182.33 g (0.13 mole) of a polyester diolwith a OH number of 80 and containing ketone functions (available fromNeoResins as PEC-205), 12.06 g (0.09 mole) of dimethylol-propanoic acidand 94.4 g of N-methylpyrolidone were heated to 70° C. while stirring.88.8 g (0.4 mole) of IPDI was added and the mixture was heated to 100°C. and stirred for 2 hrs to form a polyurethane prepolymer. After 1 hrof reaction time 0.04 g of tinoctoate was added as catalyst. Thereaction was cooled down and the amount of remaining NCO appeared to be2.87%.

110 g of the polyurethane prepolymer was mixed with 4.28 g of DMAEMA and4 g of dioctyl sodium sulphosuccinate and the mixture was dispersed into120 g of water. 1.79 g of hydrazine hydrate in 4.2 g of water was addedwithin 5 min and the dispersion was stirred for 30 min. The NCO-signalin the IR-spectrum at 2240 cm⁻¹ was disappeared.

4.28 g of butyl acrylate was added and polymerisation of the DMAEMAtogether with the butyl acrylate was effected within one hour at 75-80°C. The obtained product was adjusted with water to a solids amount of35.0% and had a pH of 7.0.

Example 11

Preparation of an aqueous polyurethane dispersion which is copolymerizedwith a tertiary amine functional methacrylate and with butylmethacrylate.

24.14 g (108.6 mmole) of IPDI was added to a mixture of 53.2 g (26.6mmole) of the polycarbonate diol of example 1, 1.5 g (3.57 mmole) of apolypropylene glycol diol with a molecular weight of 420 and 3.52 g (25mmole) of 2,2-dimethylol-propanoic acid in 12 g of N-methylpyrrolidoneat 60° C. while mixing. The mixture was heated to 90° and the mixturewas reacted at 90° C. for 2 hrs. After 1 hr of reaction time 0.01 g oftinoctoate was added as a catalyst.

The reaction mixture was cooled down. The amount of NCO in the obtainedprepolymer was 4.40%.

0.006 Gram of inhibitor MEHQ (methylether of hydroquinone) was added to94.07 gram of the prepolymer at 75° C. After stirring for ten minutes,5.92 g (51 mmole) of 2-hydroxyethylacrylate was added. The reactionmixture was stirred for 3 hours at 75-80° C. and then cooled down to 55°C. The resulting intermediate prepolymer was partially capped with thehydroxy ethylacrylate and had a NCO-amount of 1.79%.

The prepolymer was neutralised by mixing 1.49 gram of DMAEMA with 37.05gram of the intermediate prepolymer at 55° C. for 20 min. 1.88 gram ofdioctyl sodium-sulfosuccinate was mixed with 1.88 gram ofN-methyl-pyrrolidone and added to the prepolymer mix. The neutralizedprepolymer mix was dispersed in demineralised water for 45 minutes andthe polyurethane prepolymer was chain extended with hydrazine. Theabsence of residual NCO was checked by IR-spectroscopy.

2 gram of dioctyl sodium sulphosuccinate and 1.35 gram of butylmethacrylate were added to 88.3 gram of the polyurethane dispersion. Thetertiary amine functional acrylic monomer together with the double bondsof the polyurethane and of the butyl methacrylate was polymerised at 75°C. using 0.05 gram of t-butylhydroperoxide and 1.5 gram of a 1%iso-ascorbic acid solution in water. A post-treatment of 1 hour was madewith the same portions of initiators.

The obtained dispersion had a solids amount of 36.4% and a pH of 7.2

Comparative Examples 12-15

Preparation of polyurethane dispersions in which triethylamine is theneutralization agent for carboxylic acid groups.

The process of example 2, 3, 6, and 7 were repeated with the exceptionthat the DMAEMA was replaced by a stoichiometric amount oftriethylamine, and the products were adjusted to a solids amount of 35%.Triethylamine is a conventional neutralizing agent for the carboxylicacid functions in the polyurethane. The comparative examples 12, 13, 14,and 15 correspond with respectively the examples 2, 3, 6, and 7.

Example 16

This example is concerned with the evaluation of the films of theproducts of example 2, 3, 6, 7, 12, 13, 14, and 15.

Films of 200 and 600 μm were prepared of the products of example 2, 3,6, 7 and of the corresponding comparative examples 12, 13, 14, and 15.Further films were prepared of the products of example 6 and 14 togetherwith XR-5350, is a NCO-crosslinker obtainable from Stahl Holland. Themechanical properties of the films were determined. Further the weightincrease of the films in water was measured after treatment of the filmswith water for 24 hours. The results are presented in table 1. Theresults show that the film properties of the polyurethanes from whichthe carboxylic acid functions were neutralized with DMAEMA, whereafterthe DMAEMA was polymerised by addition polymerisation, were comparablewith those from which the carboxylic acid functions were neutralized bytriethylamine. They had comparable mechanical properties and thesensitivity towards water was just slightly less, but had noconsequences in application onto leather. During the drying process thepolymerized DMAEMA stayed in the film, while the triethylamine wasevaporated.

TABLE 1 weight increase of the Mechanical properties films Film of(MPa)^(a)) in water example M-100 M-200 M-300 Elongation (%) 3 4.5 6.411.0 370 14 4 3.5 5.1 7.5 420 12 6 5.3 7.8 13.2 340 13  6 + XR-5350 15.422.6 — 250 4 7 3.9 6.0 9.6 360 15 12 4.4 6.3 10.7 360 17 13 3.6 5.2 7.6460 15 14 5.5 7.9 13.6 320 15 14 + XR-5350 15.7 23.0 — 240 6 15 4.0 6.29.9 350 19

note to table 1:

a) MPa is megapascal (10⁶ Nm⁻²). The mechanical properties and theelongation are measured with films which were stretched at a thicknessof 200 μm on a MTS Synergie 200 apparatus. The values at M-100, M-200,M-300 give tensile strenghts of the films while stretching them forrespectively 50, 100, 150, 200, 300%. The elongation is the maxisalelongation before the film breaks.

What is claimed is:
 1. A process for the preparation of an aqueousdispersion of an anionic polyurethane in which initially a tertiaryaminofunctional acrylic monomer of formula I:

wherein R, R¹, R², R³, R⁴ and R⁵ are organic groups which have noreactivity towards the double bond or the tertiary amine function orwherein R, R¹ and/or R² are H; is used as neutralizing agent for pendantcarboxylic acid groups in dispersions of a polyurethane or apolyurethane-polyacrylate, whereafter the unsaturated monomers undergoin situ an addition polymerization; and wherein the aqueous dispersionof the anionic polyurethane is prepared by the steps of preparing anisocyanate functional anionic polyurethane prepolymer, containingcarboxylic acid functions.
 2. A process according to claim 1, in whichthe isocyanate terminated prepolymer is reacted with 0-100% of astoichiometric amount of a hydroxy functional unsaturated monomer beforethe dispersion of water.
 3. A process according to claim 1, in which atertiary amine functional acrylic oligomer or polymer is formed duringthe process by radical polymerization of tertiary amine functionalunsaturated monomers.
 4. A process according to claim 1, in which thetertiary amine functional unsaturated monomers react together with othervinylic monomers during the radical polymerization to obtain a tertiaryamine functional co-polymer.
 5. A process according to claim 1, whereinthe tertiary amine functional unsaturated monomer is adimethylaminoalkyl acrylate, a dialkylaminoalkyl methacrylate, adialkylaminoalkoxy acrylate and/or a dialkyl-aminoalkoxy methacrylate.6. A process according to claim 1, wherein the tertiary amine functionalunsaturated monomer is dimethylaminoethyl acrylate, diethylaminoethylmethacrylate, diethylaminoethyl acrylate, diethylaminoethylmethacrylate.
 7. A process according to claim 1, wherein the tertiaryamine functional unsaturated monomer is present in a ratio to theanionic residues to be neutralized in the polyurethane prepolymer frombetween approximately 0.3 to
 2. 8. A process according to claim 1,wherein the amount of carboxylic acid functions in the isocyanatefunctional polyurethane prepolymer is from approximately 1 weight % to15 weight %.
 9. A process according to claim 2 wherein the hydroxyfunctional unsaturated monomer is a hydroxy functional acrylate ormethacrylate selected from the group consisting of hydroxyethylacrylate, hydroxyethyl methacrylate, hydroxy-propyl acrylate,hydroxypropyl methacrylate, hydroxybutyl acrylate, hydroxybutylmethacrylate, and hydroxy-polyester acrylate or methacrylate.
 10. Aprocess according to claim 4, wherein the other vinylic monomers areselected from acrylic or methacrylic alkyl esters.
 11. A processaccording to claim 10, wherein the other vinylic monomers are present inan amount of approximately 0 weight % to 90 weight %.
 12. A processaccording to claim 1, wherein the polyurethane and/or the acrylicmonomers contain additional functional groups selected from the groupconsisting of polyalkoxy functions with a large concentration of ethoxyfunctions, tertiary amine or quaternary amine functions, perfluorfunctions, incorporated silicon functions, hydrazide functions orhydrazone functions, ketone, acetoacetate, hydroxy, methylol, amide,glycidyl, and ureido or aldehyde functions.
 13. A process according toclaim 1, wherein a conventional non-ionic, anionic or cationicsurfactant is applied during the dispersion of the prepolymer solutionin water.
 14. A dispersion prepared by the process of claim
 1. 15. Acoating or film obtained from a dispersion prepared by the process ofclaim
 1. 16. A process according to claim 1 wherein R groups arehydrogen.
 17. A process according to claim 1 wherein the step ofpreparing an isocyanate functional anionic polyurethane prepolymercomprises, in the presence of vinylic monomers, mixing the isocyanateterminated anionic polyurethane prepolymer with one or moretertiary-amino functional unsaturated monomer and then dispersing theobtained mixture into water, and chain extending the polyurethaneprepolymer with an active hydrogen compound during or after thedispersion in water, thereby initiating radical polymerization of thevinylic monomers including the tertiary amino functional unsaturatedmonomers.
 18. A process according to claim 17 wherein the preparing stepis performed in the presence of vinylic monomers other than thetertiary-amino functional unsaturated monomers.